Generally a communication route formed by a plurality of communication devices is controlled by the control plane so as to establish the end-to-end path route over such a communication network as the optical transmission network. The service level on the communication route is designated by the minimum condition of the communication path required by the user during signaling for setting the route. Determination with respect to establishment of the condition required by the user upon formation of the communication route allows an arbitrary portion of the communication route to be set for assuring the user's request. (Refer to Japanese Laid-open Patent Publication No. 2002-300192.)